The invention relates to a valve pistol, in particular for a high pressure cleaning device, with a pistol housing with a handle, with a valve placed in the pistol housing that is opened against the system pressure by a force transmission element that produces an opening movement of a valve body, with a hand lever mounted so that it can be pivoted on a swivel pin in the pistol housing on the handle over a certain pivoting path and has an actuating arm that comes to rest against the force transmission element, where the force transmission element can be shifted by an actuating arm over a determined actuation path, and where, between the hand lever and the actuating arm, there is a certain lever ratio.
The known valve pistol, relative to which the invention represents a further development (German 3 518 492) has a ball valve with a spring loaded valve ball as a valve body. When the valve body is closed, the essential force component is the component from the system pressure. The force required for opening the valve results as a product of the system pressure and the cross-section area of the valve seat. By the lever ratio of the hand lever, the actuating path is determined. For the lever ratio there exists, per se, a lower limit, which is determined by the available swing gear of the hand lever and the minimum required actuating travel of the plunger.
In contrast to other known valve pistols, during initial opening of the above-noted valve, a large lever ratio is provided since the actuating arm is very short in comparison with the hand lever. Thus, during the initial opening of the valve body at a system pressure of 250, bars for example, a reduction of the opening force on the hand lever down to 20 to 30 N can be achieved instead of the previously known 100 N. By a second swivel pin, which starts to function after the opening of the valve, it is simultaneously achieved that, when the valve body is open, the necessary holding force is as small as before, in other words, for example, it amounts only to about 10 N.
Moreover, the holding force can be even further reduced when the valve body is opened by working with a double lever gear reduction (DE-C 3 527 922) or by using a toggle drive (GB-A 513 013). However, both have significant disadvantages, namely, they are extremely expensive to construct and in turn lead, in any case, with the toggle drive, to a loss in lever arm when the valve body is opened, and thus to an increase in the opening force.